Apparatus for use in the attachment of heels to shoes



June 17, 1952 J. F. LEAHY x-:rAL

APPARATUS FOR USE IN THE ATTACHMENT OF HEELS TO SHOES 6 Sheets-Sheet 1 Filed Aug. 7, 1948 A 0 ,l fz As i N f I6 In/UQTLOPS James F Leahy John w Ashley /LeLrAztorney June 17, 1.952 J, F. LEAHY ETAL APPARATUS FOR USE IN THE ATTACHMENT OF HEELS TO SHOES Filed Aug. '7, 1948 6 Sheets-Sheet 2 @M nLAH @E nm IJJOQWd June 17, 1952 J F LEAHY 2,600,507

APPARATUS FOR USE IN THE ATTACHMENT OF' HEELS TO SHOES Filed Aug. 7, v1948 6. Sheets-Sheet 3 James F Leahy John WAS/z l e y By hez'r' Af orney June 17, 1952 J, F, EAHY El-AL 2,600,507

APPARATUS FOR USE IN THE ATTACHMENT OF' HEELS TO SHOES Filed Aug. '7, 1948 Sheets-Sheet 4 fn/efl/ORS James E' Leahy John W Ashley By heir Azforney June 17, 1952 J. F. LEAHY r-:rAL 2,600,507

APPARATUS FOR USE IN THE ATTACHMENT 0F HEELS To SHOES Filed-Aug. 7, 1948 6 Sheets-Sheet 5 11o Inventors James FLeaz John W Ashley Bg HleirAor-Ley )Cyb- June 17J 1952 J. F. LEAHY Erm.

APPARATUS FOR USE IN THE ATTACHMENT OF HEELS TO SHOES 6 Sheets-Sheet 6 Filed Aug. '7, 1948 Inl/en ions James FLea/'z John, W Ashleyy Patented June i7, 1952 APPARATUS FDR USE IN THE ATTACHMENT 0F HEELS TO SHGES .Eames F. Leahy and John W. Ashley, Beverly, Mass., assignors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application August 7, 194s, serial No. 43,046

(c1. is-so) 6 Claims. l

rIhis invention relates to shoe machinery and is herein illustrated as embodied in an apparatus for use in the attachment of heels to shoes.

It has been proposed, as disclosed for example in United States Letters Patent No. 2,447,512, granted August 24, 1948, in the name of James F. Leahy, permanently to attach a heel toY a shoe by thermoplastic resin which is injected into opposite undercut cavities in the heel seat of the shoe and the attaching face of the heel after the heel has been clamped against said heel seat and which, after iilling said cavities and also filling all voids formed between the attaching face of the heel and the heel seat of the shoe and being allowed sulicient time to harden, serves as a rivet for securing the heel permanently to the shoe.

In the attachment o wood heels to shoes in accordance with the above practice the heel of the shoe is clamped with heavy molding pressure against the heel seat of the shoe and softened thermoplastic resin is thereafter injected under high substantially sustained pressure through a passage extending heightwise of the heel and terminating at the tread end of the heel into the above-mentioned undercut cavities and voids. It will be appreciated that the amount of pressure which in the attachment of the wood heel to the shoe may be applied to the heel without breaking it is limited and also that the pressure under which quick setting thermoplastic resin must be injected into the cavities and voids in order to be effective is substantial. It has been found that when a heel is attached to a shoe in accordance with the above practice there is a tendency for the thermoplastic resin to seep outfrom between the heel seat of the shoe and the rim or the breast edge of the attaching face of the heel with the result that the iinish of the shoe is impaired. Such seepage is usually caused by the high pressure of the softened thermoplastic resin which is injected between the heel seat of the shoe and the attaching face of the heel opposing and thus rendering less effective the heavy molding pressure of the heel against the heel seat of the shoe. It will thus be apparent that when the pressure of the viscous or softened thermoplastic resin between' the heel and the heel seat of the shoeV reaches a certain point it reduces the heel attaching pressure sufficiently 2 Y to cause the heel to move slightly away from its molding position upon the heel seat of the shoe in which position it is desirable that the heel remain during and after its attachment to theA shoe.

Such movement of the heel from its molding." position upon the heel seat of the shoe may or may not be accompanied by the above-mentioned seepage but impairs the ygeneral ,appearanceoi the shoe since the heel doesnotv thenv merge attractively with the counter portion of the shoe.

It is an object of the present invention to provide an improved apparatus for quickly and ef-j fectively attaching heels to shoes by the use of thermoplastic resin. With the above considerations in View there is disclosed herein anim-j proved method of permanently securing together two parts of an article, for example, a shoe and a heel, said method comprising providing the attaching face of the heel and the heel seat' of the shoe with opposing anchoring cavitiesffcing the heel with heavy pressure against thev heel seat of the shoe, injecting under high pres"- sures a mass of viscous thermoplastic material'- into said cavities and also into voids formed between the heel and the heel seat of the shoe untilsaid cavities and voids are almost filled, reducing' radically the pressure under which the thermi-`v plastic material is injected into the cavities and;y voids as said cavities and voids become filled, and maintaining the heel forced with heavy pressure against the heel seatof the shoe until the ma# terial has set. 1 Y

The heel and the shoe constructions hereinafter illustrated are generally similar to .those disclosed in said Patent No. 2,447,512. After the' heel has been clamped against the heel seat'. of the shoe, softened thermoplastic material which' is of the resinous type andwill hereinafter be' referred to as resin is forcedthrough a passage` in the heel corresponding tothe above-mentionedpassage by an injector or dispensing gunY having a nozzle which lits in the tread end of said pas-f sage,` the resin lling the undercut cavities inthe heel and the heel seat of the shoe and also nlling the voids between said heel seat and the attach` ing face of the heel. In order' quickly and elico-` tively to' illl said cavities and voids with i'lheri'no-v plastic resin and also tov avoid the above-merli tioned drawbacks the illustrative injector is adapted initially to force the softened thermoplastic resin into the cavities and voids under high nozzle pressure of approximately 1600 pounds per square inch which is thereafter reduced below 3.90 pounds per square inch, for example, so that when the cavities and voids are approximately filled and the resin pressure between the heel seat of the shoeand the heel begins to build up, the injecting nozzle pressure will be below 390 thereby insuring against moving the heel away from its proper molding position upon the heel seat of the shoe and also insuring against the above-mentioned seepage of the resin.

The injector or dispensing gun comprises a chamber for receiving softened thermoplastic resin, a plunger slidable in said chamber, a spring for constantly urging the plunger into the charnber, a passage for receiving the thermoplastic resin under heavy pressure and for delivering it to said chamber causing displacement of the plunger and compression of the spring, a nozzle constructed and arranged to lit the above-mentioned heel passage communicating with said cavities in the heel and the heel seat of the shoe, a passage for conducting the softened resin from the chamber to the nozzle, and a valve movable in one direction in said last-named passage to prevent now of resin from the chamber to the nozzle and movable into another position to enable iiow of resin under decreasing pressure of the spring-pressed plunger through said nozzle and through the passage in the heel into said cavities.

There is also disclosed herein a modified injector or gun similar to the above-described injector but comprising heavy and light springs, both of which operate upon the plunger causing a predetermined mass of softened thermoplastic resin quickly and effectively partially to fill the above-mentioned cavities and voids, the light spring alone thereafter operating upon the plunger to complete the lling of said cavities and voids.

Softened thermoplastic resin is supplied by a suitable electrically operated extruder. Each injector comprises a coupling and the extruder has secured to it an extruder head. By opera-tively connecting the coupling of the injector to the extruder head softened thermoplastic resin may be quickly and effectively supplied to the ejector from the extruder. When the resin receiving chamber of each of the injectors has received the proper amount of resin which amounts consists of a mass slightly greater than that required to fill the cavities and voids in the largest shoe to be operated upon, the extruder is automatically stopped and cannot again be started until a manually operated switch is actuated.

By causing under iinal expanding action of a strong spring as in the case of the first described injector, or by causing under the action of the weak spring in the case of the modified injector, thermoplastic resin to be forced into the abovementioned cavities and voids in sufcient quantities to rlll said cavities and voids then partially filled, there is little if any tendency to build up pressure between the heel and the heel seat of the shoe, to a point which will cause displacement of the heel from its proper clamped position against the heel seat of the shoe or which will cause the above-mentioned seepage of thermoplatic resin between the heel and the shoe.

The various features of the invention will be understood and appreciated from the following 4 detail description read in conjunction with the accompanying drawings in which Fig. 1 is an exploded view showing in perspective a composite insole, partly broken away and heel seat and sock lining tucks prior to their assembly in the manufacture of a shoe to which a heel is to be attached by thermoplastic resin in accordance with our improved heel attaching method;

Fig. 2 shows in perspective a heel and the rear end of a shoe, partly broken away, which is ready to receive a heel;

Fig. 3 is a longitudinal median section through the rear end of the shoe and the heel shown in Fig. 2 after the heel has been clamped with moldin'g pressure against a heel seat of the shoe preparatory to being permanently attached to the shoe;

Fig. 4 is a section on line IV--IV of Fig. 3 after the thermoplastic resin has been injected into the undercut cavities in the heel seat of the shoe and the heel and has been allowed to set to attach the heel permanently to the shoe;

Fig` 5 is an angular View of an injector or gun by the use of which the thermoplastic resin is injected into said cavities, coupled to an extruder from which the injector receives its supply of softened thermoplastic resin;

Fig. 6 is a section on line VI-VI of Fig. 5;

Fig. 7 is a section on line VII-VII of Fig. 6;

Fig. 8 is a side elevation, partly broken away and partly in section, showing a heel clamping machine and the injector shown in Figs. 5, 6 and 7 in the process of injecting the resin into the undercut cavities of the heel seat of the shoe and the attaching face of the heel clamped against the shoe;

Fig. 9 is a vertical section corresponding to Fig. 6 showing portions of a slightly modified injector or gun;

Fig. 10 is a wiring diagram showing electrically operated means for controlling the extruder and accordingly the lling of the injector;

Fig. 1l is an enlarged side view of the heel clamping machine shown in Fig. 8; and

Figs. 12 and 13 are angular views showing in detail portions of a heel engaging member of said heel clamping machine.

As explained in the above-mentioned Patent No. 2,447,512, in the manufacture of womens shoes I8 (Figs. 3, 4, S and ll) it has been proposed to attach a wood heel of the Cuban type to the heel seat 22 (Fig. 2) of the shoe by thermoplastic resin, for example, while the heel is clamped under molding pressure to the heel seat of the shoe, said resin being injected into a passage or bore 26 (Figs. 2, 3, 4, 8 and 11) extending heightwise through the heel and filling undercut reentrant or anchoring cavities 2B (Figs. 2 and 3) 3! (Figs. 2, 3 and 4) in the attaching face 32 of the heel and the heel seat 22 respectively as well as all voids or spaces 3d (Figs. 3 and 4) formed between the attaching face of the heel and the heel seat. The cavity 28 in the attaching face 32 of the heel 2i) comprises a pair of intersecting undercut slots 35 having the appearance of the letter X as viewed when looking down on said attaching face of the heel. The illustrated slots 36 extend into close proximity to the rim 38 (Fig. 2) of the attaching face 32 of the heel and have central intersecting portions which are in register and communicate with the passage 26 in the heel through which the resin 2d is injected.

The shoe i8 comprises the composite insole 4B (Figs. l, 2, 3 and 4) reinforced by the heel seat and sock lining tucks 44 and 48 which are made of fibre or other suitable material; an upper` 48,

theheel end or counter portion 58 of which con-V sists of a layer of outer leather 52, a libre counter 54 and a lining 56, all suitably seWed together, heel seat lasted and secured to the heel seat of the reinforced insole by tacks 58; a metal shank stiffener 80 which is secured at its forward end to the reinforced insole 48 by staples (not shown) and an outsole 62 (Figs. 2 and 3) which is adhesively secured to a roughened overlasted margin 64 (Fig. 2) of the shoe upper 48 and the heel seat of which has been reduced to provide a heel seat tab 68 and heel breast receiving shoulders 88 engaged in the finished shoe by the forward end of the attaching face 32 and the breast 'I8 (Fig. 3) respectively of the heel.

The composite insole 40 consists of a forepart 12 (Fig. 1) and a paper-board shank and heel seat portion 'I4 interfitted and cemented together. The undercut cavity in the heel seat 22 of the shoe I8 is formed by providing in the heel seat of the composite insole 40 an opening 18 (Figs. 1 and 2) having finger portions 'I8 extending close to the heel seat margin of the sole, and forming in the heel seat tuck 44 prior to its attachment to the insole, an opening 80 slightly smaller than the central part of the opening '16, the constructionand arrangement being such that when the sock lining 46 and the heel seat tuck 44 are cemented to the composite insole 48 there are formed a plurality of undercut finger portions of the cavity 38. It will be noted that the rear end of the shank stiffener 88 extends into the void or space between the undercut cavities 28, 30 in the attaching face 32 of the heel and the heel seat 22 of the shoe I8 and that when viscous thermoplastic resin is forced under pressure through the passage 26 into the heel by the use of a gun of the type described in said Patent No. 2,447,512, the resin fills the undercut cavities 2.8, 30 and all voids 34 between the heel seat 22 of the shoe and the attaching face 32 of the heel and if desirable approximately all of the passage 28 as best shown in Fig. 4.

Preparatory to the permanent attachment of the heel 28 to the shoe I8 the rim 38 of the attachingface 32 of the-heel is forced with heavy molding pressure against the outer edge of the overlasted margin 82 (Figs. 2, 3 and 4) of the counter portion 58 of the shoe and the breast 10 (Fig. 3) of the heel 20 is forced against the heel breast receiving shoulders 68 (Fig. 2), the forwardV end of the attaching face of the heel resting upon the heel seat tab 86. It is desirable that the overlasted heel seat margin 82 of the shoe shall be planar so that the entire rim 38 of the attachingv face 32 of the heel shall exert uniformly distributed pressure against said margin, said rim usually molding or depressing the margin slightly asbest shown in Figs. 3 and 4. The lasted margin 82 instead of lbeing fiat commonly has high and low spots and accordingly it is necessary to force the rim 38 of the heel 20 with heavy molding pressure against the heel seat of the shoe before and While the .heel is being attachedV to the shoe in order. to insure that the rim of the heel shall hug and` merge attractively with the counter portion of the shoe. As previously explained the amount of pressure that can be appliedagainst the wood heel without damaging it i-n forcing it against the heel seat of the shoe is limited, 500 pounds being about the maximum pressure commonly' used in the attachment of the average-Cuban heel to the shoe.

` In the attachment of'heels to shoes by the use of thermoplastic resin which sets fairly rapidly it has been the practice to injec'trthe softened resin into the cavities 28, 30 in theattaching face 32 of the heel and the heel seat 22 of the shoe and into the voids 34 between the attachingface of the heel and said heel seat undera substantially uniformly high and sustained nozzle pressure, for example, of about 1600 lbs. persquare inch in order to insure that the resin shall be effectively injected into and ll such cavities and voids before having a chance substantially kto set. As above explained when heels are being attached to shoes by viscous thermoplastic res-- in injected into thev cavities and voids under sustained heavy pressure there is a tendency for the heel to be raised slightly away from its proper molding position upon the heel seat of the shoe and also for the resin to seep out between the counter portion of the shoe I8 and-the rim 38 of-the attaching face 32 of the heel and/or beitween the forward edge of the attaching face of the heel and the shank portion of the outsole. Such conditions as abovev explained are due to the fact that whensoftened resin is injected into the cavities 28, 30 and the voids 3 4' after said cavities and voidsare substantially` full, a high pressure is built up beneath the attaching face of the heel, such pressure opposing and thus reducing the lpressurel which is forcing the heel against the heel seat of the shoe.

With the foregoing considerations in view we propose to force, as above explained, under high pressures a substantial quantity or mass of softened thermoplastic resinintc the cavities 28, 38

and the voids 34, `a' remaining quantity or mass of softened resin necessary to ll the undecut cavities and voids being injected into said cavities and voids at low pressures, so that pressures imparted to the mass of resin substantially lling the cavities and voids shallnot be great enough to oppose the heel clamping pressure sufficiently to cause the. above-mentioned undesirable conditions.

There are disclosed herein two injectors or guns for use in practicing our method, Figs. 5, 6, 7 and 8 illustrating an injector or gun 84 which injects softened thermoplastic resin at initially high but gradually diminishing pressures into the cavities 28, 30 and the voids 34 and Fig. 9 illustrating an injector or gun 8S which is substantially like the above-mentioned injector but which injects a predetermined amount of softened thermoplastic resin into said cavities and voids under high diminishing pressures and then injects into the cavities and voids under low diminishing pressures an amount of softened thermoplastic resin necessary to ll said cavities and voids. Y

The injector 84 receives softened resin from an extruder 88 (Figs. 5 and 6) of any suitable commercial type in which said resin is electrically heated and has a bore 90 (Figs. 6 and 10) along which the resin is advanced under pressure by a screw 92 rotated by an electric motor 93 (Fig. 10). There is secured to the extruder 88 byscrewsl 94 (Fig. 6) a head or coupling head 96 which has a stepped passage or conduit 98 forming'an extension of the extruder bore 80, said passage having in its outer end a shoulder against which a fine mesh screen |08 is forced by the extruded resin. The screen |88 stops flow of the softened resin from the conduit 88 into` a passage 102 in a cylindrical nozzle |84 ofthe extruder head 96 when the screw 92 of the extruder 86 is at rest.

The injectors or dispensing guns 84, 86 Vwhen full hold .a quantity or mass of resin slightly greater than that required to ll the cavities 28, 30 and the voids 34 in the attachment of a heel to the largest shoe operated upon, said guns having secured to them by screws |06 a locking plate or coupling |08 for quickly and eiectively coulpling the guns to the extruder 96,V as will be explained later, preparatory to receiving a new charge of viscous thermoplastic resin. 1 A

The injector 34 has a steel barrel ||0 (Figs. 6 and 8), the periphery of which is recessed for receiving an electric heater ||2, there being secured to the barrel a casing I4 (Figs. 5, 6 and 8) for covering said heater. The barrelV I is bored to provide a cylindrical resin receiving recess or chamber ||6. Threaded onto the barrel ||0 and insulated from portions of it by an insulating washer ||8 is an aluminum spring housing |20 having at its lower end a cylindrical recess |22 and having threaded into its upper end a cap |24. Slidingly mounted in the chamber I6 is a hollow plunger |26 which has an enlarged iianged portion |28 tted for sliding movement in the recess |22 of the housing |20, a heavy spring` |30 which is interposed between the anged portion |28 of the plunger and the cap |24 of the housing serving constantly to urge the plunger into the chamber.

Screwed onto the barrel is a valve block |32 having a two-part tapering recess or passage |34,` an upper portion of which isl in alinement with the lower end of the chamber'l I6 and into which opens an inlet passage or conduit 36 ,for receiving viscous thermoplastic resin. To the lower end ofthe valve block |32 is secured a nozzle |38 which has a shoulder |39 (Figq) and is constructed and arranged to iit in the passage or bore 26 in the rheel 20 and which has a passage |40 in communication with the lower portion of the tapered recess |34. Formed in the valve block |32 is a bore |42 serving as a bearing for a rotary valve |44 having a tapering recess |46 which may be moved into alinement with the upper and lower portions of the tapering recess |34 to permit resin in the chamber ||6 to be forced by the spring actuated plunger|26 out through the passage |40 of the nozzle |38 or V which may be moved into its position shown in Fig. 6 to cut off communication between the upper and lower portions of the recess ,|34 and accordingly ejection of thermoplastic resin from the nozzle. The rotary valve |44 may be described as being movable only transversely of the passage |34 from an open position to a closed position to close communication between the chamber 6 and the nozzle |36.

The coupling or locking plate |98 which is secured by the screws |06 to the valve block |32 and may be considered as part of the injector or gun has formed in it a cylindrical resin inlet passage or conduit |48, a valve guide provided with arcuate slots |52 connecting the passage |48 to the passage |36, being clamped between opposing shoulders of the coupling |08 and the valve block |32. Freely Isliding in a bore of the valve guide |50 is a valve |54 which has a frusto conical head |56 constructed and arranged to seat on a frusto conical port |58 of the coupling |08. The valve .|54 slides to the left, as viewed in Fig. 6, in the guide |50 to an extent determined by the engagementof a collar |60 of the valve with the guide under the action of the incoming softened thermoplastic resin forced from the extruder into the passage |48. After the thermoplastic resin has passed under extrusion pressure through the passage |43, the arcuate perforations |52 and the passages |36, |34 into the chamber H6 it raises the plunger |26 against the action of the spring |30, the chamber continuing to iill until the upper end or" the plunger engages a normally closed microswitch |62 which is carried by the cap |24 of the spring housing |20 and is secured tothe cap by a terminal housing |63 thereby breaking a holding circuit |55 and accordingly deenergizing a solenoid operatedswitch |51 to cause the opening of a. circuit |66 for the extruder motor 93. 1n order to insure against starting the extruder 66 when the plunger |26 moves away from the microswitch |62 and until the actuation of a normally open switch |68 in a solenoid circuit |59, there is provided the above-mentioned holding circuit |55 which after the release of the switch |60 keeps the solenoid operated switch |51 energized until the opening of the microswitch |62. It will be apparent from the wiring diagram shown in Fig. l0 that once the microswitch |62 has beenvactuated to deenergize the solenoid operated switch |51 said switch cannot again be energized until the manually operated switch |60 is actuated. YThere is also provided in the holding circuit |55'a safety switch I1|.

Various thermoplastic materials are suitable for use in the practicing of our method. An example of one composition which may be used successfully is as follows:

Parts by weight Ethyl cellulose (50 or 100 centipoise rviscosity) ethoxy content, 45.0-46.5% 250 Diphenyl (O-Xenyl) phosphate 50 Phenolic resin 30 Menthyl phenol Y4.5 Calcium stearate 3.0

Injection of thermoplastic resin from the gun 84, the plunger |26 of which has been moved to a cocked position by the viscous thermoplastic resin entering the chamber H6, may be readily effected by rotating the valve |44 to a position in which the tapering recess |46 connects the upper and lower portions of the tapering recess |34, the recesses |34, |46 forming in eii'ect a continuous tapered recess. The valve |44 is controlled by a rack |16 (Figs. 6 and 7 which meshes with a pinion |12 secured to the valve and which is slidably mounted in guideways |14 (Fig. 1) formed in spaced projecting ears |16 (Figs. 5, 6 and 7) of the valve block |32. The rack |10 carries a pivot pin |18 upon which is mounted a block |90 into which is threaded the lower end of a rod |82, the upper end of said rod being pivotally connected to a lever |64 journaled on a pivot pin 86 carried by a bracket |88 clamped by a screw |31 to the spring housing |20. The rack |10 may be initially adjusted with relation to the rod |02 to insure that the tapering recess |46 may be moved into its proper stop position in alinement with the tapering recess |34, after loosening a lock nut |00 which is threaded onto the rod and may be clamped against the block to maintain .the rod in its adjusted position with relation to the block. Surrounding the rod |02 and interposed between the nut |90 and the bracket |89 is a spring |92 for constantly urging the rack |16 downward until shoulders |94 (Fig. 7) of the valve |44 engage the ears |16 of the valve block 32. Secured by screws |96 (Figs. 5 and 8) to the ears |16 of the valve block |32 and to the bracket |88 is a wood. handle |98 which is used by the operator in handling and operating the ejector or gun, said lever |84 having secured to it by screws 298 a wood hand piece 262 which when depressed raises the rack |76 into a position in which the tapering recess |46 is in alinernent with the upper and lower portion of the tapered recess |34, such position being determined by the engagement of the shoulders |94 of the valve |44 with the ears |16 of the valve block |32.

The injector coupling |08 has a cylindrical throat or intake nozzle 206 which overrides and may be described as intertting telescopically with the nozzle |04 of the extruder head 98 until a conical face or sealing portion 208 (Fig. 6) of the injector coupling is forced against an opposed complemental conical face or sealing portion 209 of said extruder head. The injector 84 may be forced into and held in its adhesive receiving position in the socket formed in the extruder head as shown in Figs. and 6. This socket has a frusto conical face 209 at its inner end and, when the injector has been seated in the socket, the conical faces 208 and 289 of the coupling |08 and the extruder head 96 are in v engagement. They are held in rm contact by upper and lower spiral cams 2I0, 2|2 which are formed on brackets 2|4, 2 |6 respectively secured by screws 2 I8 to the extruder head 96, said cams being constructed and arranged to be engaged by spiral faces 220, 222 of the coupling |08 as the injector is rotated clockwise as viewed in Fig. 5 into its proper position shown in Figs. 5 and 6 to receive softened thermoplastic resin from the extruder 88. It will be apparent that when the injector or gun 84 is rotated counterclockwise as viewed in Fig. 5 to permit it to be released from the extruder 96, the valve |54 is slid to the right as viewed in Fig. 6 by pressure of the thermoplastic resin within the injector, causing the head |56 of the valve |54 to close the port |58.

It is important that the temperature of the thermoplastic resin 24 in the various parts of the injectors or guns 84, 86 be retained suiciently high to insure the proper ilow of said resin into the undercut cavities 28, 30 in the attaching face 32 of the heel 26 and heel seat 22 of the shoe I8 and into the voids 34 between the attaching face of the heel and the heel seat of the shoe. Accordingly, the extruder head 96 has inserted in it four electric heaters 224 (only two shown) (Fig. 5) and the valve block has two electric heaters 226 (only one shown). Moreover, it is important that the nozzle |38 be kept hot while the gun is not in use. Accordingly, there is provided an electrically heated shroud or yoke 228 having a slot 230 in which the nozzle |38 of the gun 84 or 86 is moved when the gun is being moved to its resin receiving position shown in Figs. 5 and 6 in the extruder head 96. The heating yoke 228 is secured to the eXtruder head 98 by bolts 232 (only one shown) extending through recesses (not shown) in the yoke and threaded into the cam bracket 2 I 6. The yoke 228 is'heated by a plurality of electric heaters 233 (only one shown). In presenting either of the injectors or guns 84, 86 to the extruder head 96 the cylindrical throat 206 of the locking plate |88 is slid onto the cylindrical nozzle |04 of the extruder head 96, the nozzle |38 of the gun being arranged to the right, as viewed in Fig. 5, of the notch 238 of the heated yoke 228 and the spiral faces 228,

and at one side of the spiral cams 2 I0, 2 |2 of the brackets 2 |4, 2 6 secured to the extruder head 96. The injector or gun 84 or 86 is then rotated clockwise as viewed in Fig. 5 causing the upper and lower spiral faces 220, 222 of the coupling |08 to override the spiral cams 2|0, 2|2 of the brackets 2|4, 2|6 thereby forcing the conical face 208 of the coupling |08 against the conical face 209 of the extruder head 96 and causing the nozzle |38 of the injector to be swung into the slot 230 of the yoke 228.

In order readily to determine the temperatures lof the extruder head 96, the valve block |32 and the nozzle heating yoke 228 there are provided thermometers 234 (Fig. 5) having stems 236 fitting in recesses 238 of the Various members.

As above explained the injector or gun 84 (Figs. 5, 6, 7 and 8) may be replaced by the injector or gun 86 illustrated in Fig. 9 in order quickly and eifectively to inject under heavy pressure into the undercut cavities 28, 30 in the attaching face 32 of the heel and the heel seat 22 of the shoe and into voids 34 formed between the attaching face of the heel and the heel seat of the shoe a quantity or mass of softened thermoplasticresin f which will iill a large percentage of said cavities and voids, and thereafter to inject into said cavities and voids under light pressure a quantity of softened thermoplastic resin sufficient to flll said cavities and voids. 'Ihe injector or gun 86 which may be referred to as a modified injector, except for hereinafter described parts, is similar to the injector or gun 84 and comprises a spring housing 240 (Fig. 9) which corresponds to ther spring housing |20 and has a cylindrical recess 242. Interposed between a cap 244 threaded into and forming part of the housing'240 and a, flange 246 at the lower end of a drum 248 slidable in the recess 242 is a heavy or strong spring 250. Slidably movable in a cylindrical resin receiving recess or chamber 252 substantially like the recess or chamber |I6 of the injector or gun v84 is a, plunger 254, the upper end of which is slidable in a guideway 256 of the drum 248, said plunger having formed in it a bore 258 for receiving a relatively light or weak spring 260, the upper end of which engages a spring retaining projection 2,62 of the cap 244. The plunger 254 is constantly urged to its lowered position in the resin chamber 252 by the springs 250 and 260 the lower limit of travel of the plunger 254 in the chamber 252 being determined by the engagement of a flange 264 of the plunger with a stop or face 265 of the housing 240. Upward movement of the plunger 254 with relation to the drum 248 is limited by engagement of the flange 264 of the plunger with a stop or face 266 of the drum.

It will thus be clear that when viscous thermoplastic resin is forced under pressure into the cylindrical chamber 252 the plunger 254 is raised against the action of the relatively light spring 288 until the flange 264 of the plunger engages the face 266 of the drum 248, the plunger and the drum thereafter being moved upward together against the action of the heavyl spring 258 and the light spring 260 under pressure applied to the plunger by the softened thermoplastic resin entering said chamber. As in the injector or gun 84, rotation of the extruder screw 92 and accordingly upward movement of the drum under the action of the viscous resin forced into the gun by the extruder 88 is limited by the. engagement of the upper end of the drum withY a microswitch 268 correspondingto the 'micro- .switch 162. As above explained in connection with the injector or gfun .bfi once the .extruder .88 has been stopped, the switch `1 is has .to be manually operated in order .again to .star-t the .extruden Thejheel 2.? maybe .quickly and .effectively forced .against the heel seat A22 .of the shoe i' by the use of the `machine or clamp which is illustrated in Figs. 8, 11, 12 and 13 and which as will appear later is .constructed fand .arranged to enable the nozzle 138 of the injector or gun or 86 to be inserted into the passage or Shore 2B .of the heel clamped .against the' .heel seat .of the shoe.

The illustrative heel clamping machine cornprises va frame 2.1i) (Figs. .8 and 11) which is bolted .to a bench (not shown) or other suitable .support and has secured to it by screws 2i2 a fulcrum screw 21M a yoke 21e. Slidingly adjustable on a guide portion 218 (Figs. l1 and i9) at the upper .end of the yoke 22e is a split supporting bracket 260 having a pair of forwardly .extending bifurcations `2132, the bracket Ybeing secured in .diierent adjusted positions en said .guide portions by a .binding screw 281i. `Pivotally supported in alined bor-es 265 of the bifurcations `2112 are pins 288 which are secured by screws 28| .to a tread .end abutment or plate .29e (Figs. 1l and 13) and which .are pinned to a' pair of vrearwardly extending arms 292 into the rear ends of which are threaded screws 294 extending through slots 28o in a U-shaped gage supporting member 298 arranged in guideways 22S (Fig. 13') formed in said arms. The abutment 2%53 has a flat lowerheel engaging surface a :tapered opening 322 through which the nozzle 138 of the injector is inserted preparatori.1 to injecting resin into the passage 25 of the heel 25 to be attached to the shoe 18.

Adjustable into diierent forward and rearward positions 'ina guideway 39d (Fig. 13) of the gage supporting member 238 after releasing the locking screw 356 is a V-shaped back 308 constructed and arranged to be engaged by the rear face of the heel, the abutment Edi! and the back gage ses being movable as a unit into a predetermined angular operating position about an axis 31B (Fig. 13) oi the pins 2&3 against a screw 312 which is threaded into the split bracket 2% and is engaged by an abutment 315 forming part of the gage supporting member 298. It will be clear that the abutment 29D and the back gage 3513 may be moved as a unit into diierent angular positions about the axis 31E, the friction between the pins and the forwardly extending bifurcations of the bracket being suihcient to retain the abutment block 3M in its operating position against the stop screw 312.

The back gage ii may be moved into different adjusted positions along the guideway of' the supporting member 2538 and may he moved` into diierent adjusted positions generally heightwise or" the heel by raising or lowering the gage supporting member 29s along the guideways of the arms 292. The various members which are supported by the bifurcations 282 and cornprise the abutment 22@ and the back gage 3523 may be described as a holder.

Theshoe 18 mounted upon a last or form is supported in the illustrative heel clamping machine by a knurled support A3 iulcrumed on a pin 32D secured to a lever 322 which is pivotefl upon the fulcrum screw 215i, said lever having cylindrical recess 324 for receiving an upper 12 ball end 325 of a manually operated thrust inember or screw 328 threaded into the yoke 2`i. The lever 322 is constantly urged against .the ball end 32d of the screw 323 by a spring 338, opposite ends of which are attached to hooks iixed to the lever 322 and to the yoke 276. The fulcrum screw 2id is so positioned with relation to the yoke Z'i that when the lever 322 moves clockwise as viewed in Figs. 8 and 11 upon upward advancement of the screw 323 in the yoke, .said lever moves the support Sie, then in engagement with the cone of the last 316 upon which the shoe is mounted, heightwise and rearward of the shoe. The heightwise and rearward components of movement ci the knurled support 31.3 carried by the lever .322 'may be varied by moving the yoke E'i into difierentadjusted positions upon the frame 27% so as to change .the location of the fulcrum screw 2id about which the lever 322 pivots with relation to the yoke 2%.

In practicing .our improved heel vattaching method the operator places the heel '20 upon the fitted heel seat 22 of the shoe 18 andafter moving the tread face of .the heel assembled with the shoe into engagement with the lower face 360 of the abutment 2950 and the rear face of the heel into engagement with the back gage 3118, operates the screw 32E! to force the knurled support 31,3 against the cone of the last 3HE upon which the shoe is mounted.

Preparatory to assembling the heel and the shoe the pivotally mount-ed holder which comprises the abutment 293 .and the heel gage 308 is moved to its frictionally held operative position against the screw 312. Clockwise rotation of the hand screw 328 as viewed from below causes the lever 322 to swing clockwise as viewed in Figs. 8 and 1l with the result that the knurled support 318 is moved upward and rearward causing the heel seat 22 of the shoe to be forced with considerable pressure against the attaching face of the heel held against movement by the abutment 298 and the back gage 3% and the heel breast receiving shoulders 13S of the sole S2 of the shoe to be forced against the breast of the heel with considerable pressure. The upward and rearward components of movement of the support 318 may be varied to increase or decrease the amount of pressure of the heel breast receiving shoulders SS against the breast 'iii of the heel by changing the position of the yoke 21S with relation to the axis of the iulcrum screw 2M.

In order permanently to attach the heel 2G to the shoe 18 by thermoplastic resin 24 after clamping the heel against the heel seat 22 of the shoe in the heel clamping machine above described, the operator grips the handle 193 (Figs. 5, 6 and 8) of the injector S65 which is then in its position illustrated in Fig. 5 and the chamber 116 of which has beeniilled with thermoplastic resin, and rotates the injector counterclockwise to move the spiral faces 229, 222 of the coupling 163 from behind the spiral faces 211i, 212 of the extruder head 98 and to swing the injector nozzle |33 out of the slot 232i of the heating yoke 222, the spring ist (Fig. 6) of the injector then being compressed. The injector i'is then bodily transferred to the heel clamp and the nozzle 138 of the injector is inserte-d through the opening 362 in the abutment 2%5! and into the passage or bore 2S of the heel, the ange 139 of the nozzle resting on the upper face of said abutment.

The handle 2&2 of the injector M is then depressed causing the thermoplastic resin in the chamber 1 15 to be forced with gradually decreesing pressure 'into the undercut cavities, 28, 30 in the attaching face 32 of the heel 20 and the heel seat 22 of the shoe as well as into the voids 34. When the cavities 28, 3B and the voids 34 have been lled with resin the passage 26 in the heel starts to fill and the injector is moved out of the passage under pressure of the resin which progressively 'fills said passage. As the end of the nozzle |38 approaches the top lift receiving face of the heel the operator releases the handle 282 of the injector and moves the injector away from the work, the injector again being placed in its thermoplastic receiving position shown in Fig. on the extruder head 96 to receive, after the switch |68 has been manually closed another supply of thermoplastic resin preparatory to operating upon the next shoe. The screw 328 is then released and the shoe which has been operated upon is removed from said machine.

The practicing of the method by the use of the injector illustrated in Fig. 9 is substantially the same as that above described, the only difference being that the thermoplastic resin is ejected from the chamber 352 first under the action of the springs 258, 260 and thereafter under the action of spring 260.

The method practiced in securing two parts of an article together or in attaching a heel to a shoe by the use of the mechanism disclosed herein is claimed in an application for United States Letters Patent Serial No. 135,362, led December 28, 1949, in our names and the machine or apparatus for use in clamping heels to shoes in practicing the above method is claimed in an application for United States Letters Patent Serial No. 250,902, filed October 11, 1951, in our names.

Having described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. In an injector for use in the permanent attachment to the heel seat of a shoe of a heel which is temporarily clamped against said heel seat and which has in its attaching face an anchoring cavity in opposed relation to an anchoring cavity in the heel seat of the shoe, a chamber for receiving softened thermoplastic resin, a plunger slidable in the chamber, a resin receiving conduit which communicates with said chamber and through which softened resin under heavy pressure may be forced into the chamber with displacing action on the plunger, a valve for opening and closing said conduit, a nozzle tting in a bore which is formed in the heel and through which the resin is injected into said cavities, an outlet passage between the chamber and the nozzle, a member which is movable relatively to the plunger and acts on the plunger, a stop, a heavy spring for moving said member in one direction, a predetermined distance limited by the stop against the plunger and accordingly for moving the plunger a predetermined distance into an inner end of the chamber to force under heavy pressure into the cavities of the heel and the heel seat of the shoe a mass of softened thermoplastic resin insuicient to fill the cavities, and a light spring operative to move the plunger relatively to said member after engagement of said member with the stop to force into said cavities under low pressure another mass of softened thermoplastic resin suicient to complete the filling 0f said cavities.

2. The combination of a hollow dispensing gun provided with a displaceable plunger and an extruder for filling the gun, said extruder having an outlet and power operated means for delivering a softened plastic material to the gun through an opening therein, cooperating tting surfaces on the gun adjacent to said opening and on the extruder adjacent toits outlet, means for holding said surfaces in firm engagement, a control device responsive to the movement of displacement of the plunger in the gun, and a connection between said control device and the power operated means for the extruder for stopping the extruding action on the completion of a predetermined displacement of said plunger.

3. In combination, a power driven extruder having an outlet opening, a socket associated with said outlet opening, a dispensing gun temporarily positioned in said socket in tight relation to the outlet opening, said gun being provided with a displaceable plunger moved by the advancing material pressed by the extruder into the gun, a switch actuated by the movement of the plunger at a predetermined point in its travel, a device for controlling the application of power to said extruder drive, and means operated by said switch for actuating said device.

4. In combination, an extruder provided With a screw mechanism for forcing a softened thermoplastic material out of the outlet of the eX- truder, a dispensing gun having a filling opening temporarily positioned to receive material from said outlet, said gun having a plunger which is physically displaced an appreciable amount by the thermoplastic material pushed into the gun by theextruder, a drive for the screw mechanism, electrically operated means for controlling said drive, a switch actuated by the displaced plunger as the gun is being lled, and electrical connections between said switch and the drive control for rendering the drive ineffective when the gun has been iilled.

5. In combination, an extruder having an opening leading into a socket provided with a frusto conical surface at its inner end, a dispensing gun having a displaceable plunger, said gun being provided with a projecting portion terminating in a frusto' conical surface fitting the corresponding surface of the socket of the extruder, coacting cam faces on the extruder and the gun rendered operative by a partial turning movement of one with respect to the other to lock the projecting portion of the gun in the socket of the eXtruder, and a controllable drive for the extruder rendered ineffective when the gun has been lled.

6. The combination of an extruder and an injector which has a chamber for receiving softened thermoplastic resin from the extruder and has a plunger constantly urged into said chamber and displaceable in said chamber under pressure of the resin entering said chamber, said injector and extruder having cooperating portions respectively for coupling the injector to the eX- truder preparatory to receiving softened thermoplastic resin from the extruder and for uncoupling the injector from the extruder preparatory to injecting said resin into a Work piece, electrically powered means for operating the extruder, said means comprising a circuit, a solenoid operated switch movable into an active position to close said circuit and from said active position to open said circuit, a solenoid circuit comprising a manually operated normally open switch, a holding circuit for maintaining closed the solenoid circuit once it has been established even though the manually operated switch is open, and a micro-switch which is operative when the injector plunger has been moved to a predetermined position under the action of softened 15 I6 thermoplastic resin injected into the chamber UNITED STATES PATENTS to open said holding circuit thus causing move- I vmbe Name Date ment of the solenoid operated switch away from 2 lig 373 Crevelng May 24 1933 its actve'positon and accordingly the stopping 23269514 Brandt an 13: 1942 0f the exm'udel* 5 2,299,195 Ushakoff occ. 2o, 1942 JAMES F. LEAHY.

2,306,788 MacDonald Dec. 29, 1942 JOHN W' ASHLEY 2,431,843 swager Dec. 2', 1947 I Y 4 2,435,647 Engseth Feb. 10, 1948 REFERENCES CITED 2,4391506 Christian Apr. 13J 1948 The followmg references are of record 1n the 10 447,512 Leahy Aug. 24, 1948 me 0f this Patenti 625 stuart sept. 21, 194s 

